. >> reporter: he still hasn't recovered, and a joint investigation by abc news and the food and environment reporting network found more than 100 reported illnesses due to blue-green algae exposure. >> essentially if we don't solve this problem, somebody's going to >> reporter: ohio state's dr. jeffery reutter is the foremost authority on blue-green algae. he says it's a nationwide problem, largely caused by farm fertilizer runoff. the cure, he says, is convincing farmers to carefully fertilize so the nutrients stay on the fields and not in the water. >> otherwise, these blooms are going to continue to grow. the human health problems that we see are going to increase. >> reporter: assaulting our senses, our economy and our health. jim avila, abc news, lake petenwell, wisconsin. >> our thanks to jim tonight. >>> and in los angeles, a bridge demolition that forced officials to shut one of america's busiest highways, the 405 freeway went as plan and carmageddon didn't happen. the lanes are expected to re-open as planned for the morning commute. >>> there is still much more ahead on "world news